Re: [Xen-users] "Booted on L1TF-vulnerable hardware with SMT/Hyperthreading enabled" .. or not?

[Hans van Kranenburg <hans@xxxxxxxxxxx>]

On 09/03/2018 12:14 AM, Andrew Cooper wrote:
> On 02/09/18 21:22, Hans van Kranenburg wrote:
>> On 08/31/2018 02:12 AM, Hans van Kranenburg wrote:
>>> On 08/31/2018 02:09 AM, Hans van Kranenburg wrote:
>>>> I have some HP ProLiant DL360 G7 (P68) servers here, and I just put this
>>>> BIOS update on them:
>>>>
>>>> https://support.hpe.com/hpsc/swd/public/detail?swItemId=MTX_23267b7aabb6489a8332d06919#tab3
>>>>
>>>> Version: 2018.05.21(2 Jul 2018)
>>>>
>>>> The release notes contain a whole story about "This revision of the
>>>> System ROM includes the latest revision of the Intel microcode which, in
>>>> combination with operating system and hypervisor updates, provides
>>>> mitigation for the L1 Terminal Fault – OS/SMM (CVE-2018-3620) and L1
>>>> Terminal Fault – VMM (CVE-2018-3646) security vulnerabilities."
>>>>
>>>> In the BIOS cpu settings, hyperthreading is disabled. This server
>>>> contains 2x 6-core Intel(R) Xeon(R) CPU X5675 @ 3.07GHz
>>>>
>>>> From xen info: (4.11, built from stable-4.11 commit 733450b39b)
>>>>
>>>> -# xen info
>>>> host                   : rho
>>>> release                : 4.17.0-0.bpo.3-amd64
>>>> version                : #1 SMP Debian 4.17.17-1~bpo9+1 (2018-08-27)
>>>> machine                : x86_64
>>>> nr_cpus                : 12
>>>> max_cpu_id             : 31
>>>> nr_nodes               : 2
>>>> cores_per_socket       : 6
>>>> threads_per_core       : 1
>> From server startup serial console:
>>
>> ---- >8 ----
>>                             108 GB Installed
>>
>>
>>
>> ProLiant System BIOS - P68 (05/21/2018)
>>
>> Copyright 1982, 2018 Hewlett-Packard Development Company, L.P.
>>
>>
>>
>>
>> 2 Processor(s) detected, 12 total cores enabled, Hyperthreading is disabled
>> Proc 1: Intel(R) Xeon(R) CPU X5675 @ 3.07GHz
>> Proc 2: Intel(R) Xeon(R) CPU X5675 @ 3.07GHz
>> QPI Speed: 6.4 GT/s
>> HP Power Profile Mode: Custom
>> Power Regulator Mode: Static High Performance
>>
>> Advanced Memory Protection Mode: Advanced ECC Support
>> Redundant ROM Detected - This system contains a valid backup system ROM.
>> Inlet Ambient Temperature: 20C/68F
>>
>> ---- >8 ----
>>
>> "Hyperthreading is disabled"
>>
>>>> Still, xl dmesg shows me:
>>>>
>>>> (XEN) ***************************************************
>>>> (XEN) Booted on L1TF-vulnerable hardware with SMT/Hyperthreading
>>>> (XEN) enabled.  Please assess your configuration and choose an
>>>> (XEN) explicit 'smt=<bool>' setting.  See XSA-273.
>>>> (XEN) ***************************************************
>>>>
>>>> What's wrong here?
>>> Additionally:
>> So, interestingly, this information (from dom0) lists ht again in flags:
>>
>>> -# cat /proc/cpuinfo
>>> processor   : 0
>>> vendor_id   : GenuineIntel
>>> cpu family  : 6
>>> model               : 44
>>> model name  : Intel(R) Xeon(R) CPU           X5675  @ 3.07GHz
>>> stepping    : 2
>>> microcode   : 0x1f
>>> cpu MHz             : 3066.788
>>> cache size  : 12288 KB
>>> physical id : 0
>>> siblings    : 4
>>> core id             : 0
>>> cpu cores   : 1
>>> apicid              : 0
>>> initial apicid      : 0
>>> fpu         : yes
>>> fpu_exception       : yes
>>> cpuid level : 11
>>> wp          : yes
>>> flags               : fpu de tsc msr pae mce cx8 apic sep mca cmov pat 
>>> clflush acpi
>>> mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl
>>> nonstop_tsc cpuid pni pclmulqdq monitor est ssse3 cx16 sse4_1 sse4_2
>>> popcnt aes hypervisor lahf_lm ssbd ibrs ibpb stibp
>>> bugs                : null_seg cpu_meltdown spectre_v1 spectre_v2 
>>> spec_store_bypass l1tf
>>> bogomips    : 6133.57
>>> clflush size        : 64
>>> cache_alignment     : 64
>>> address sizes       : 40 bits physical, 48 bits virtual
>>> power management:
>>>
>>> (identical for all cpus listed)
>> Another view on the thing, from dmidecode:
>>
>> Handle 0x0400, DMI type 4, 42 bytes
>> Processor Information
>>      Socket Designation: Proc 1
>>      Type: Central Processor
>>      Family: Xeon
>>      Manufacturer: Intel
>>      ID: C2 06 02 00 FF FB EB BF
>>      Signature: Type 0, Family 6, Model 44, Stepping 2
>>      Flags:
>>              FPU (Floating-point unit on-chip)
>>              VME (Virtual mode extension)
>>              DE (Debugging extension)
>>              PSE (Page size extension)
>>              TSC (Time stamp counter)
>>              MSR (Model specific registers)
>>              PAE (Physical address extension)
>>              MCE (Machine check exception)
>>              CX8 (CMPXCHG8 instruction supported)
>>              APIC (On-chip APIC hardware supported)
>>              SEP (Fast system call)
>>              MTRR (Memory type range registers)
>>              PGE (Page global enable)
>>              MCA (Machine check architecture)
>>              CMOV (Conditional move instruction supported)
>>              PAT (Page attribute table)
>>              PSE-36 (36-bit page size extension)
>>              CLFSH (CLFLUSH instruction supported)
>>              DS (Debug store)
>>              ACPI (ACPI supported)
>>              MMX (MMX technology supported)
>>              FXSR (FXSAVE and FXSTOR instructions supported)
>>              SSE (Streaming SIMD extensions)
>>              SSE2 (Streaming SIMD extensions 2)
>>              SS (Self-snoop)
>>              HTT (Multi-threading)
>>              TM (Thermal monitor supported)
>>              PBE (Pending break enabled)
>>      Version: Intel(R) Xeon(R) CPU X5675 @ 3.07GHz
>>      Voltage: 1.4 V
>>      External Clock: 133 MHz
>>      Max Speed: 4800 MHz
>>      Current Speed: 3067 MHz
>>      Status: Populated, Enabled
>>      Upgrade: Socket LGA1366
>>      L1 Cache Handle: 0x0710
>>      L2 Cache Handle: 0x0720
>>      L3 Cache Handle: 0x0730
>>      Serial Number: Not Specified
>>      Asset Tag: Not Specified
>>      Part Number: Not Specified
>>      Core Count: 6
>>      Core Enabled: 6
>>      Thread Count: 12
>>      Characteristics:
>>              64-bit capable
>>
>> This also lists hyperthreading and 6 cores with 12 threads per physical
>> cpu...
>>
>> The code which decides about printing the message or not does:
>>
>> if ( opt_smt == -1 && cpu_has_bug_l1tf && !pv_shim &&
>>      boot_cpu_data.x86_num_siblings > 1 )
>>     warning_add(
>>         "Booted on L1TF-vulnerable hardware with SMT/Hyperthreading\n"
>>         "enabled.  Please assess your configuration and choose an\n"
>>         "explicit 'smt=<bool>' setting.  See XSA-273.\n");
>>
>> (from commit 2a47c75509, author in Cc)
>>
>> Apparently in here, boot_cpu_data.x86_num_siblings > 1 still matches
>> when hyperthreading is actually disabled in bios configuration?
>>
>> Is there a better way to detect configuration (enabled/disabled) vs.
>> just the fact that the hardware has the feature and could enable it?
>> Something like the same source as where xl info gets the
>> threads_per_core from, which does show up as 1?
> 
> The HT flag in CPUID is of no use in this case.  It is actually
> HyperThreadingTechnology which is a bit signalling that other topology
> related information in the CPUID leaves has changed from the legacy
> enumeration mechanisms.  Most hardware in the last 10 years sets the HTT
> bit, even on non-HT capable hardware.
> 
> Do you have the full Xen boot log (`xl dmesg` once dom0 has booted) ?
> 
> Xen's boot_cpu_data.x86_num_siblings ought to be correct, but I'd agree
> in this case it appears to be in direct contradiction to what the
> firmware claims.

(XEN) parameter "placeholder" unknown!
(XEN) Xen version 4.11.1-pre (Debian
4.11.1~pre+1.733450b39b-1~exp1~mxbp9+1) (hans@xxxxxxxxxxx) (gcc (Debian
6.3.0-18+deb9u1) 6.3.0 20170516) debug=n  Wed Aug 22 15:26:44 UTC 2018
(XEN) Bootloader: GRUB 2.02~beta3-5
(XEN) Command line: placeholder dom0_max_vcpus=4 dom0_mem=4G,max:4G
com2=115200,8n1 console=com2,vga noreboot xpti=no-dom0
(XEN) Xen image load base address: 0
(XEN) Video information:
(XEN)  VGA is text mode 80x25, font 8x16
(XEN)  VBE/DDC methods: none; EDID transfer time: 2 seconds
(XEN)  EDID info not retrieved because no DDC retrieval method detected
(XEN) Disc information:
(XEN)  Found 1 MBR signatures
(XEN)  Found 1 EDD information structures
(XEN) Xen-e820 RAM map:
(XEN)  0000000000000000 - 000000000009f400 (usable)
(XEN)  000000000009f400 - 00000000000a0000 (reserved)
(XEN)  00000000000f0000 - 0000000000100000 (reserved)
(XEN)  0000000000100000 - 00000000d762f000 (usable)
(XEN)  00000000d762f000 - 00000000d763c000 (ACPI data)
(XEN)  00000000d763c000 - 00000000d763d000 (usable)
(XEN)  00000000d763d000 - 00000000dc000000 (reserved)
(XEN)  00000000fec00000 - 00000000fee10000 (reserved)
(XEN)  00000000ff800000 - 0000000100000000 (reserved)
(XEN)  0000000100000000 - 0000001b27fff000 (usable)
(XEN) New Xen image base address: 0xd7000000
(XEN) ACPI: RSDP 000F4F00, 0024 (r2 HP    )
(XEN) ACPI: XSDT D7630140, 00B4 (r1 HP     ProLiant        2   �     162E)
(XEN) ACPI: FACP D7630240, 00F4 (r3 HP     ProLiant        2   �     162E)
(XEN) ACPI: DSDT D7630340, 20BD (r1 HP         DSDT        1 INTL 20030228)
(XEN) ACPI: FACS D762F100, 0040
(XEN) ACPI: SPCR D762F140, 0050 (r1 HP     SPCRRBSU        1   �     162E)
(XEN) ACPI: MCFG D762F1C0, 003C (r1 HP     ProLiant        1             0)
(XEN) ACPI: HPET D762F200, 0038 (r1 HP     ProLiant        2   �     162E)
(XEN) ACPI: FFFF D762F240, 0064 (r2 HP     ProLiant        2   �     162E)
(XEN) ACPI: SPMI D762F2C0, 0040 (r5 HP     ProLiant        1   �     162E)
(XEN) ACPI: ERST D762F300, 01D0 (r1 HP     ProLiant        1   �     162E)
(XEN) ACPI: APIC D762F500, 015E (r1 HP     ProLiant        2             0)
(XEN) ACPI: SRAT D762F680, 0570 (r1 HP     Proliant        1   �     162E)
(XEN) ACPI: FFFF D762FC00, 0176 (r1 HP     ProLiant        1   �     162E)
(XEN) ACPI: BERT D762FD80, 0030 (r1 HP     ProLiant        1   �     162E)
(XEN) ACPI: HEST D762FDC0, 00BC (r1 HP     ProLiant        1   �     162E)
(XEN) ACPI: DMAR D762FE80, 0146 (r1 HP     ProLiant        1   �     162E)
(XEN) ACPI: SSDT D7632400, 0125 (r3     HP  CRSPCI0        2   HP        1)
(XEN) ACPI: SSDT D7632540, 01CF (r3     HP  riser1a        2 INTL 20061109)
(XEN) ACPI: SSDT D7632740, 03BB (r1     HP      pcc        1 INTL 20090625)
(XEN) ACPI: SSDT D7632B00, 0377 (r1     HP     pmab        1 INTL 20090625)
(XEN) ACPI: SSDT D7632E80, 2094 (r1  INTEL PPM RCM         1 INTL 20061109)
(XEN) System RAM: 110581MB (113235768kB)
(XEN) Domain heap initialised DMA width 32 bits
(XEN) IOAPIC[0]: apic_id 8, version 32, address 0xfec00000, GSI 0-23
(XEN) IOAPIC[1]: apic_id 0, version 32, address 0xfec80000, GSI 24-47
(XEN) Enabling APIC mode:  Phys.  Using 2 I/O APICs
(XEN) Failed to get Error Log Address Range.
(XEN) Speculative mitigation facilities:
(XEN)   Hardware features: IBRS/IBPB STIBP L1D_FLUSH SSBD
(XEN)   Compiled-in support: INDIRECT_THUNK SHADOW_PAGING
(XEN)   Xen settings: BTI-Thunk RETPOLINE, SPEC_CTRL: IBRS- SSBD-,
Other: IBPB L1D_FLUSH
(XEN)   L1TF: believed vulnerable, maxphysaddr L1D 44, CPUID 40, Safe
address 10000000000
(XEN)   Support for VMs: PV: MSR_SPEC_CTRL RSB EAGER_FPU, HVM:
MSR_SPEC_CTRL RSB EAGER_FPU
(XEN)   XPTI (64-bit PV only): Dom0 disabled, DomU disabled
(XEN)   PV L1TF shadowing: Dom0 disabled, DomU enabled
(XEN) Using scheduler: SMP Credit Scheduler (credit)
(XEN) Platform timer is 14.318MHz HPET
(XEN) Detected 3066.791 MHz processor.
(XEN) Initing memory sharing.
(XEN) [VT-D]Disabling IOMMU due to Intel 5500/5520/X58 Chipset errata
#47, #53
(XEN) I/O virtualisation disabled
(XEN) Enabled directed EOI with ioapic_ack_old on!
(XEN) ENABLING IO-APIC IRQs
(XEN)  -> Using old ACK method
(XEN) Allocated console ring of 32 KiB.
(XEN) VMX: Supported advanced features:
(XEN)  - APIC MMIO access virtualisation
(XEN)  - APIC TPR shadow
(XEN)  - Extended Page Tables (EPT)
(XEN)  - Virtual-Processor Identifiers (VPID)
(XEN)  - Virtual NMI
(XEN)  - MSR direct-access bitmap
(XEN)  - Unrestricted Guest
(XEN) HVM: ASIDs enabled.
(XEN) HVM: VMX enabled
(XEN) HVM: Hardware Assisted Paging (HAP) detected
(XEN) HVM: HAP page sizes: 4kB, 2MB, 1GB
(XEN) Brought up 12 CPUs
(XEN) Dom0 has maximum 816 PIRQs
(XEN)  Xen  kernel: 64-bit, lsb, compat32
(XEN)  Dom0 kernel: 64-bit, PAE, lsb, paddr 0x1000000 -> 0x266a000
(XEN) PHYSICAL MEMORY ARRANGEMENT:
(XEN)  Dom0 alloc.:   0000001adc000000->0000001ae0000000 (1025804 pages
to be allocated)
(XEN)  Init. ramdisk: 0000001b2650c000->0000001b27dffa74
(XEN) VIRTUAL MEMORY ARRANGEMENT:
(XEN)  Loaded kernel: ffffffff81000000->ffffffff8266a000
(XEN)  Init. ramdisk: 0000000000000000->0000000000000000
(XEN)  Phys-Mach map: 0000008000000000->0000008000800000
(XEN)  Start info:    ffffffff8266a000->ffffffff8266a4b4
(XEN)  Xenstore ring: 0000000000000000->0000000000000000
(XEN)  Console ring:  0000000000000000->0000000000000000
(XEN)  Page tables:   ffffffff8266b000->ffffffff82682000
(XEN)  Boot stack:    ffffffff82682000->ffffffff82683000
(XEN)  TOTAL:         ffffffff80000000->ffffffff82800000
(XEN)  ENTRY ADDRESS: ffffffff82433180
(XEN) Dom0 has maximum 4 VCPUs
(XEN) Initial low memory virq threshold set at 0x4000 pages.
(XEN) Scrubbing Free RAM on 2 nodes using 12 CPUs
(XEN)
.........................................................................done.
(XEN) Std. Loglevel: Errors and warnings
(XEN) Guest Loglevel: Nothing (Rate-limited: Errors and warnings)
(XEN) ***************************************************
(XEN) Booted on L1TF-vulnerable hardware with SMT/Hyperthreading
(XEN) enabled.  Please assess your configuration and choose an
(XEN) explicit 'smt=<bool>' setting.  See XSA-273.
(XEN) ***************************************************
(XEN) 3... 2... 1...
(XEN) Xen is relinquishing VGA console.
(XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch
input to Xen)
(XEN) Freed 476kB init memory

I can reboot with another loglevel if needed.

Hans

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